docs(nuxt): Add Nuxt's Nitro features (#15286)

Adds entries on the newly added and available Nitro instrumented
features released in `10.17.0` and `10.21.0`.

Author: logaretm

docs/platforms/javascript/guides/nuxt/features/nitro-server-features.mdx

@@ -0,0 +1,40 @@
+---
+title: Nitro Server Features
+description: "Learn which Nitro server features are automatically instrumented by the Sentry Nuxt SDK."
+---
+
+The Sentry Nuxt SDK automatically instruments various Nitro server APIs to provide performance monitoring and error tracking for your server-side code.
+
+## Server Middleware
+
+<Alert>Available from version `@sentry/nuxt` 10.17.0 and up.</Alert>
+
+The Sentry Nuxt SDK automatically instruments [server middleware handlers](https://nuxt.com/docs/4.x/guide/directory-structure/server#server-middleware) in addition to server event handlers. This includes the handler functions and their `onBeforeResponse` and `onRequest` callbacks.
+
+## Cache
+
+<Alert>Available from version `@sentry/nuxt` 10.21.0 and up.</Alert>
+
+The Sentry Nuxt SDK automatically instruments [cache APIs](https://nitro.build/guide/cache) for the following Nitro functions:
+
+- `defineCachedEventHandler`
+- `cachedEventHandler`
+- `cachedFunction`
+
+This provides spans in your transactions that represent cache operations and their durations, including cache hits.
+
+## Storage
+
+<Alert>Available from version `@sentry/nuxt` 10.21.0 and up.</Alert>
+
+The Sentry Nuxt SDK automatically instruments [storage APIs](https://nuxt.com/docs/4.x/guide/directory-structure/server#server-storage) (also known as KV storage) and common operations.
+
+Keep in mind that only the storage mounts configured under `nitro.storage` in your `nuxt.config.ts` will be instrumented. Storage spans will show up in a similar way to [cache](#cache) spans since they both utilize the same underlying Nitro storage API.
+
+## Database
+
+<Alert>Available from version `@sentry/nuxt` 10.21.0 and up.</Alert>
+
+The Sentry Nuxt SDK automatically instruments Nitro's [database API](https://nitro.build/guide/database). This provides spans in your transactions that represent database query operations and their durations, enabling you to identify slow queries, track query frequency, and optimize your database interactions.
+
+Database instrumentation only applies to database mounts configured under `nitro.database` in your `nuxt.config.ts` and only when `nitro.experimental.database` is set to `true`.